Thread-cutting die.



W. SCOTT.

THREAD CUTTING DIE. APPLICATION H'Lm) JULY 2,1906.

Patented Aug. 30, 1910.

WILLIAM SCOTT, OF MEDFORD, MASSACHUSETTS.

THREAD-CUTTING DIE.

Specification of Letters Patent. Patented Aug. 30, 1910.

Application filed July 2, 1906. Serial No. 324,403.

To all whom it may concern:

Be it known that I, IVILLIAM Soon, a citizen of the United States,residing in Medford, in the county of Middlesex and State ofMassachusetts, have invented an Improvement in Thread-Cutting Dies, ofwhich the following description, in connection with the accompanyingdrawings, is a specification, like letters on the drawings representinglike parts.

The present invention relates to a die for cutting screw threads, and isembodied in an expanding die, the purpose being to cause the chasers todisengage from the'material by a lateral movement after the threads arecut, so that the material can be withdrawn from the die withoutreversing the lathe.

A further feature of the invention consists in means for causing thechasers to disengage automatically, the disengaging means beingadjustable so as to operate after any desired length of thread has beenout.

A further feature of the invention consists in means for adjusting, to aslight degree, the position of the chasers when closed ready foroperation, so that a variation in the thread diameter is provided for,thereby affording provision for a tight or loose fit without departingmaterially from the standard size.

In accordance with the invention, the die head is provided withtransverse guides for the chasers which, in turn, are caused to movetoward each other in said guides by means of a yoke pivotally connectedwith the head and having inclined surfaces at opposite sides to engagethe outer ends of the chasers. The yoke is of substantial strength andis extended around the body of the die, so that when closed in upon the.

chasers, it forms a solid abutment therefor, capable of resisting allthe lateral strain due to the thread cutting operation. The yoke isconveniently located for operation by hand in either direction, and isalso arranged so as to be connected with a member longitudinally movablewith relation to the die head, and in the path of the material to beoperated upon, so that the material itself, at the finish of the threadcutting operation, will act to withdraw the yoke and permit thespreading of the chasers in response to the action of a spring orsprings with which they are provided for the purpose. 1

Figure 1 is a perspective view of a thread cutting die embodying theinvention; Fig. 2 is a vertical,-longitudinal section, through the axisof the die; Fig. 3 is a horizontal, longitudinal section through theaxis of the die; Fig. 4 is a front elevation showing the die closed; andFig. 5 is a similar view showing the die open or expanded.

The die a is herein shown as a rectangular block of metal cast integralwith the supporting shank a and formed hollow to permit the entrance ofthe material upon which the thread is to be cut. The head a is providedat the front with guides a and at which are shown as V-shaped tracks tofit into corresponding V-shaped grooves 6 formed along the top andbottom of the chasers b. The said chasers are shown as acted upon bysprings b which are herein shown as formed of a single wire bent arounda support a, indicated as a bolt screwed into the head at the back partof one of the guides at To close the die, that is to say, to bring thechasers into proper position to act upon the material, the outer ends ofthe chaser members 6 are acted upon by wedges cwhich are herein shown asinclined surfaces formed at the inner sides of a yoke c which ispivotally supported in a bore or opening through the die head a. Bymaking this member in the form of a yoke extending around the threesides of the head a, it is not only accessible for manipulation, but canbe made of great strength so as to resist all the strain which isbrought to bear to separate the dies in the thread cutting operation.The construction, furthermore, is sus ceptible of minor adjustment, theupper ends of the yoke 0 being supported upon a bolt 0 which extendsthrough the bearing in the die head, one end of said bolt being providedwith a screw thread 0 cooperating with a thread in one of the yokemembers, so that by turning the said bolt, the upper ends of the yokecan be sprung together to a slight extent, thereby bringing the inclinedsurfaces closer to the ends of the chasers and causing the chasers to bemoved nearer to gether.

In the construction shown, the bolt-head c is in the formof a screwhead, and the said member may further be provided with calibrations 0 toindicate the amount of adjustment, thereby practically constituting amicrometer screw.

In order to lock the parts firmly together.

after adjustment has been made, a locking screw 0 may be employed, thesaid screw being shown as extending through an opening in the end of thebolt 0 which is split so as to be slightly expanded through the actionof the screw 0. 7

In order that the opening of the die may be automatic, so that thechasers' b will expand and free themselves from the material after thedesired length of thread has been cut, the yoke is connected with asupple mental actuating member 0?, herein shown as a rod having anengaging end portion (Z which stands in the path of the material,passing into the die when being threaded; The said member at is hereinshown as adjustably connected with-a cross arm 6 which,

in turn, has links 6 pivotally connected at 6 with the sides of the yoke0 The member d is longitudinally adjustable with relation to the membere and is held in its adjusted position by means of a set screw 6*, shownas extending longitudinally into the member 6, The member d may,therefore, be set to the outside of the die head, the side members ofthe said yoke having inclined surfaces to cooperate with the chasermembers; and means acting on said yoke at its open ends to draw the saidends together for the purpose of adjustment.

, In testimony whereof, I have signed my name to this specification inthe presence of two subscribing witnesses.

WILLIAM SCOTT. Witnesses M. E. COVENEY, H. J. LIVERMORE.

